18. SOAP with Attachments API for Java
SOAP with Attachments API for Java (SAAJ) is used mainly for the SOAP messaging that goes on behind the scenes in JAX-WS handlers and JAXR implementations. Secondarily, it is an API that developers can use when they choose to write SOAP messaging applications directly rather than use JAX-WS. The SAAJ API allows you to do XML messaging from the Java platform: By simply making method calls using the SAAJ API, you can read and write SOAP-based XML messages, and you can optionally send and receive such messages over the Internet (some implementations may not support sending and receiving). This chapter will help you learn how to use the SAAJ API.
The SAAJ API conforms to the Simple Object Access Protocol (SOAP) 1.1 and 1.2 specifications and the SOAP with Attachments specification. The SAAJ 1.3 specification defines the javax.xml.soap package, which contains the API for creating and populating a SOAP message. This package has all the API necessary for sending request-response messages. (Request-response messages are explained in SOAPConnection Objects, page 638.)
The javax.xml.messaging package, defined in the Java API for XML Messaging (JAXM) 1.1 specification, is not part of the Java EE platform and is not discussed in this chapter. The JAXM API is available as a separate download from http://java.sun.com/xml/downloads/jaxm.html.
This chapter starts with an overview of messages and connections, giving some of the conceptual background behind the SAAJ API to help you understand why certain things are done the way they are. Next, the tutorial shows you how to use the basic SAAJ API, giving examples and explanations of the commonly used features. The code examples in the last part of the tutorial show you how to build an application. The case study in Chapter 36 includes SAAJ code for both sending and consuming a SOAP message.